1. Field of the Invention
This invention relates generally to telecommunications systems, and more particularly to audio signal processing for teleconferencing systems where multiple talkers share a sound transceiver.
2. Description of the Related Art
Teleconferences often have multiple talkers at a single site. Such talkers typically share a sound transceiver. A typical shared sound transceiver includes a microphone and a speaker. The sound received at the microphone is converted into an electrical signal for processing and transmission to remotely located teleconferencing participants via suitable electrical, optical, and/or wireless communication networks. The elements processing the electrical signal typically include an automatic gain control (AGC) circuit, which adjusts, by appropriate amplification or attenuation, the electrical signal so that the amplitude of the adjusted electrical signal is generally within some acceptable range. This is done so that the adjusted signal's amplitude is neither too high nor too low. The adjusted signal may undergo additional processing steps to improve sound quality (e.g., reduce noise) or increase transmission efficiency, and may be added to one or more other signals for transmission to the remote locations. Typically, the adjusted signal is eventually received at sound transceivers of the other participants and converted back to sound.
The AGC processing of the electrical signal corresponding to the received sound is typically based on the composite and time-averaged characteristics of the received sound. When a teleconference having multiple participants at a single site includes, for example, a loud talker positioned close to the microphone and a soft talker positioned far from the microphone, AGC processing based on the time-averaged characteristics of both talkers will tend to insufficiently amplify signals corresponding to the soft talker and insufficiently attenuate signals corresponding to the loud talker, resulting in less than desirable playback at the remote locations.